What Is Traumatic Brain Injury?


Maj Hemstad
A traumatic brain injury, or TBI, occurs when an external force such as a bump, blow, or jolt causes structural damage to the brain or disruption of brain function. Injuries can be focal or diffuse. When the damage occurs in a specific area of the brain, it’s called a focal injury. A diffuse injury means more than one area of the brain is damaged, or that the damage is widespread.

Lt Col Reynolds
TBI can be caused by a number of external forces, including:
  • The head being struck by a falling or flying object
  • The head striking an object, such as the windshield of a car or the ground
  • An object going through the skull and entering the brain tissue, which is called a penetrating head injury
  • The forces generated by a blast or explosion, often called a blast injury, and
  • The sudden acceleration/deceleration movement of the brain without a direct blow to the head, as in severe cases of “whiplash”

Maj Hemstad
These forces can cause nerve cells in the brain to stretch, tear, or pull apart, making it difficult or impossible for the cells to send messages from one part of the brain to another, or to other parts of the body. TBI can interfere with certain brain functions, including thinking, memory, vision, and controlling the body’s movements, often called motor skills. You can find more information about how the brain works if you visit the Interactive Brain, the Anatomy of the Brain, and Lobe Functions.

Lt Col Reynolds
Traumatic brain injury can range from mild to severe depending on several factors. To learn more about how a TBI is classified as mild, moderate, or severe, visit Classifications of TBI.